<?php
// ============================================================
//  api/db.php  —  shared PDO connection + helpers
// ============================================================

require_once __DIR__ . '/../config.php';

// Ensure PHP errors never output HTML into JSON responses
ini_set('display_errors', '0');
ini_set('display_startup_errors', '0');
error_reporting(E_ALL);

// Convert PHP errors to exceptions so they get caught properly
set_error_handler(function(int $errno, string $errstr, string $errfile, int $errline): bool {
    throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});

// Catch fatal errors and return JSON
register_shutdown_function(function(): void {
    $err = error_get_last();
    if ($err && in_array($err['type'], [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR])) {
        if (!headers_sent()) {
            http_response_code(500);
            header('Content-Type: application/json; charset=utf-8');
        }
        echo json_encode(['error' => 'Internal server error', 'detail' => $err['message']]);
    }
});

// Start session once, safely
// For OAuth flows (cross-site redirect), SameSite must be Lax (not Strict)
function start_session(): void {
    if (session_status() === PHP_SESSION_NONE) {
        $is_https = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
                 || (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https')
                 || (isset($_SERVER['SERVER_PORT']) && $_SERVER['SERVER_PORT'] == 443);

        session_set_cookie_params([
            'lifetime' => 86400,
            'path'     => '/',
            'secure'   => $is_https,
            'httponly' => true,
            'samesite' => 'Lax',  // Lax allows cookie on redirect from OAuth provider
        ]);
        session_start();
    }
}

function db(): PDO {
    static $pdo = null;
    if ($pdo === null) {
        $dsn = sprintf(
            'pgsql:host=%s;port=%s;dbname=%s',
            DB_HOST, DB_PORT, DB_NAME
        );
        $pdo = new PDO($dsn, DB_USER, DB_PASS, [
            PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES   => false,
        ]);
    }
    return $pdo;
}

function json_out(mixed $data, int $status = 200): never {
    http_response_code($status);
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode($data, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

function json_error(string $msg, int $status = 400): never {
    json_out(['error' => $msg], $status);
}

function cors(): void {
    $origin = $_SERVER['HTTP_ORIGIN'] ?? '';

    // credentials:include requires explicit origin, not wildcard
    if ($origin !== '') {
        header('Access-Control-Allow-Origin: ' . $origin);
    } else {
        header('Access-Control-Allow-Origin: *');
    }
    header('Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS');
    header('Access-Control-Allow-Headers: Content-Type');
    header('Access-Control-Allow-Credentials: true');
    if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
        http_response_code(204);
        exit;
    }
}

function require_admin(): void {
    start_session();
    if (empty($_SESSION['is_admin'])) {
        json_error('Unauthorized', 401);
    }
}

function is_moderator(): bool {
    start_session();
    if (!empty($_SESSION['is_admin'])) return true;
    $user = $_SESSION['oauth_user'] ?? null;
    if (!$user) return false;
    $stmt = db()->prepare("
        SELECT 1 FROM moderators m
        JOIN users u ON u.id = m.user_id
        WHERE m.user_id = :uid AND (u.banned IS NULL OR u.banned = false)
    ");
    $stmt->execute([':uid' => $user['id']]);
    return (bool)$stmt->fetchColumn();
}

function require_mod(): void {
    if (!is_moderator()) {
        json_error('Unauthorized — moderator access required', 401);
    }
}

function body(): array {
    $raw = file_get_contents('php://input');
    return json_decode($raw, true) ?? [];
}

function sanitize_name(string $name): string {
    return strtolower(preg_replace('/[^a-zA-Z0-9_]/', '', trim($name)));
}